Spring operated mechanism for electric circuit breakers



Oct. 30, 1962 R. LYON 3,061,698

SPRING CPERATED MECHANIsM FCR ELECTRIC CIRCUIT BREAKERS Filed Marcho,1959 2 sheets-sheet 1 /7 War/vri( Oct. 30, 1962 l.. R. LYoN 3,061,698

SPRING OPERATED MECHANISM FOR ELECTRIC CIRCUIT BREAKERS Filed March 20,1959 2 Sheets-Sheet 2 3,061,698 SPRING OPERATED MECHANISM FOR ELECTRHCCIRCUIT BREAKERS Lyman R. Lyon, Royal Oak, Mich., assignor to Square DCompany, Detroit, Mich., a corporation of Michigan Filed Mar. 20, 1959,Ser. No. 800,839 1 Claim. (Cl. 200-88) This invention relates generallyto electric circuit breakers and more particularly toa spring-operatedmechanism for automatically opening and for manually opening and closingthe separable contacts of an electric circuit breaker.

Automatic electric circuit breakers often employ a spring-operatedmechanism to facilitate the opening and closing of the separablecontacts of the circuit breaker. The design of such spring operatedmechanisms is based upon several known electrical and mechanicalrequirements. Contact pressure between the separable contacts of thecircuit breaker must be suilicient to prevent excessive heating of thecontacts. Also the force required to move a manual operator to initiatemanual opening and closing of the contacts should be kept to a minimum.In addition, it is often required that a spring-operated mechanismshould eifect separation of the contacts of the circuit breaker asrapidly as possible upon the occurrence of a fault or overload in thebranch circuit protected by the circuit breaker in order to limit thedamaging effects of short circuit current on the separable contacts ofthe circuit breaker.

The requirements of adequate contact pressure, ease of manual operation,and rapid separation of the contacts are often met, in circuit breakersknown to the art, by the use of relatively complex spring operatedcollapsible linkages that employ one or more toggle members pivotallyconnected to each other. Typically, the toggle members are connected toeach other and to a movable contact carrier by a journalled bearing inthe form of a rivet. However, every rivet employed as a pivotalconnector between two parts requires both an assembly operation and anupsetting operation during fabrication of the mechanism. Further, closetolerances must be provided in such bearings which create furtherdiculty in the manufacture, assembly, and maintenance of the mechanisms.

Accordingly, a broad object of the present invention is to provide animproved and relatively uncomplicated spring-operated mechanism for acircuit breaker that satisfes the requirements of adequate contactpressure, ease of manual operation, and rapid separation of thecontacts.

A further object of the present invention is to provide aspring-operated mechanism for a circuit breaker wherein no part isconnected to another part by a riveted connection.

Another object of the present invention is to provide an improvedspring-operated mechanism for a circuit breaker wherein an overcentertoggle biases a separately mounted contact carrier to the open andclosed contact position.

A more specific object of the present invention is to provide aspring-operated mechanism for an electric circuit breaker comprising amanual operator that is supported for rotation by the enclosure andwhich has a fulcrum thereon. A releasable member is supported forrotation by the enclosure and is normally restrained in a latchedposition by a suitable trip device. A toggle link is supported forrotation by `and upon the fulcrum on the manual operator and is biasedinto engagement therewith by an overcenter spring that extends betweenthe releasable member and the toggle link. The manual operator isrotatable in opposite directions to carry the fulcrum thereon across theline of action of the overcenter spring to States Narent Yice reversethe rotative bias of the spring on the toggle link. The toggle link isslidably connected with a movable contact carrier that is supported forrotation by the enclosure. The trip device is operative in response toabnormal circuit conditions in a circuit associated with the circuitbreaker to releaseI the releasable member, which, upon release, carriesone end of the spring, and therefore the line of action of the spring,to the opposite side of the fulcrum on the manual operator thereby toreverse the rotative bias of the overcenter spring on the toggle link.Rotation of the toggle link biases the contact carrier to the contactopen position.

Other objects and advantages of this invention will become apparent fromthe following description wherein reference is made to the drawings inwhich:

FIG. l is a side elevation of a spring-operated mechanism in accordancewith the present invention shown in the contacts closed position andsupported by a molded insulating enclosure in operative relationshipwith a trip device.

FIG. 2 is -a sectional view taken along the lines II-II of FlG. 1.

FIG. 3 is a perspective view of the handle, toggle link and contactcarrier of the circuit breaker with the parts in disengaged position forclarity.

FIG. 4 is a side elevation of the spring-operated mechanism of FIG. lafter manual operation to the contacts open position.

FIG. 5 is a side elevation of the spring-operated mechanism of FlG. 1after automatic operation of the mechanism to the contacts openposition.

Referring to FIG. 1, a spring-operated mechanism 10 in accordance withthis invention is shown operatively mounted in a circuit breaker 11. Asshown, the circuit breaker 11 comprises an insulating base 12 providedwith suitable recesses 13 and barriers 14 for supporting the componentsthereof in operative position. A cover portion 15 (FIGS. 4 and 5)complementary to the base 12 substantially encloses the components ofthe circuit breaker to form an enclosure and is preferably held inposition by a plurality of rivets 15. For use in conjunction with aplug-in panelboard, the circuit breaker 11 may be electrically connectedto one side of an external source of electrical energy by a spring jawclip 16 that extends exteriorly of the circuit breaker 11 through anopening 17 in the base 12. The circuit breaker 11 is arranged to be`mechanically supported and held within a panelboard by a spring jawclip 18. The clip 16 is electrically connected to a source terminal 19that has a fixed contact 20 mechanically and electrically securedthereto, as by welding. A movable contact 21 is supported on a movablecontact carrier 22 in operative alignment with the iixed contact 20. Thecontacts 20 and 21 are shown in the circuit closed position in FIG. l. Allexible conductor 24- is electrically and mechanically secured at oneend to the movable contact carrier 22, as by welding, and at the otherend to an insulated conductor 25 that extends from a trip device 26. Thetrip device 26 may be of any suitable construction but it is preferablyone similar to the trip device disclosed in Serial No. 744,287, filedJune 24, 1958, by Edward P. Dessert et al. and assigned to the assigneeof the present application.

The trip device 26 is electrically and mechanically connected to a loadterminal strip 28` that is maintained in position within the insulatingbase 12 as by a screw 29.

` To facilitate connection of the circuit breaker 11 to an eX- ternalload, a solderless connector or load terminal 30 is electrically andmechanically connected to the load terminal strip 28 at the outer endthereof.

The trip device 26 comprises an elongated bimetallic strip 31 that iselectrical-1y and mechanically connected,-

as by welding, at the upper end thereof as seen in the drawings, to theupper end of the terminal strip 28. A magnetic core 32 of generallyU-shapcd cross-section is attached to the lower end of the bimetalliestrip 31, as by welding. The magnetic core 32 extends upwardly generallyparallel to the bimetallic strip 31 with the leg portions thereofdisposed on opposite sides of the strip 31 and extending toward thespring operated mechanism 10 of the circuit breaker 11. The insulatedconductor Z is wound about the magnetic core 32 and is mechanically andelectrically secured to the strip 31, as by welding. The bimetallicstrip 311 and insulated conductor 25 thus carry the current of thecircuit associated with the circuit breaker and cause a flux to becreated in the magnetic core 32 that is related in amount to themagnitude of current in the circuit.

The magnetic core 32 is provided, at its upper end portion, with ahook-like armature support 34 that pivotally supports a magneticarmature 36 in operative alignment with the magnetic core 32. A helicalcompression spring 41 normally biases the armature 36 clockwise withrespect to the magnetic core 32 so as to provide an air gap between thearmature 36 and the magnetic core 32. When the amount of flux in thecore 32 exceeds a predetermined value, magnetic attraction of thearmature 36 overcomes the bias of the spring 41 and causes the armature36 to swing Counterclockwise to release the spring-operated mechanism14B of the circuit breaker 11, as will be discussed.

An ambient temperature compensating bimetallic strip 44 is attached, asby welding, to the lower end portion of the magnetic core 32 and extendsdownwardly therefrom substantially parallel to the core 32 from itspoint of attachment and upwardly inwardly of the circuit breaker toengage the lower end portion of the magnetic armature 36 on the oppositeside thereof from the bimetallic strip 31. Counterclockwise flexure ofthe bimetallic strip 31 about its point of attachment to the terminalstrip 28 upon heating thereof is transmitted through the magnetic core32 to the magnetic armature 36 by the ambient temperature bimetallicstrip 44. A latching surface 45 on the magnetic armature 36 serves tonormally latch the spring-operated mechanism 16 in the reset positionand is retracted from the latched or reset position upon movement of thearmature 36 due to exure of the bimetallic strip 31 or attraction of thearmature 36 to the magnetic core 32 upon the occurrence of an overloador fault current, respectively, in the circuit associated with thecircuit breaker 11.

The path of current through the circuit breaker 11 is from thesolderless connector 30 on the terminal strip 28 through the bimetallicstrip 3:1 and insulated conductor 25 to the iiexible conductor 24 andmovable contact carrier 22 to the movable contact 21, then to the iixedcontact 20 and source terminal strip 19 and the spring jaw clip 16.

In accordance with the present invention, the springoperated mechanismcomprises a manual operator 50 of insulating material having spacedintegral trunnions 51 thereon which are pivotally supported in suitablebearing recesses (not shown) in the insulating base 12 and cover. Themanual operator Sil has a handle portion 52 which projects lthrough anopening 53 in the top of the base 12 to facilitate manual movement ofthe operator 50 to cause operation of the mechanism 10 to open and closethe contacts 19 and 20.

An inner end portion 54 of the manual operator 50 is bifurcated to`define two legs S5 and 56 provided with fulcrum recesses 57 and '53,respectively, for the support of an elongated U-shaped toggle link 59.The U-shaped configuration of the toggle link 59 is defined by a bightportion 640 and a pair of spaced upwardly extending leg portions 61 and62. A pair of upper end faces 63 and 64 on the leg portions 61 and 62,respectively, are biased into the fulcrum recesses 57 and 53,respectively, of the manual operator 50 by an operating spring 65 thatextends between the toggle link 59 and a releasable member 66. One endportion of the spring 65 is secured in a hole 67 in the bight portion 60of the toggle link 59 and the other end portion is similarly secured ina hole 63 in the releasable member 66. The releasable member 66 issupported for rotation by an upstanding pivotal support 69 formed on thebase 12 and is releasably restrained from rotation by engagement of anend portion 7@ thereof with the latching surface 45 on the magneticarmature 36.

A pin 71 extends transversely of the toggle link 59 and is secured tothe leg portions 61 and 62 thereof adjacent and parallel to the bightportion 60, as by welding. The pin 71 is slidably engaged in a pair ofspaced aligned slots 72 and 73 extending longitudinally of the contactcarrier 22 and formed in a pair of spaced, parallel flanges 7-4 and 75,respectively, of the movable contact carrier 22. The contact carrier 22is supported for rota tion by a pin 77 that extends through alignedholes 78 and 79 in the tianges 74 and 75 of the contact carrier 22,respectively. The pin 77 is supported in suitable aligned recesses (notshown) in the insulating base 12 and cover. The pin 71 on the link 59cooperates with the slots 72 and 73 in the contact carrier 22 totransmit movement of the toggle link to the contact carrier 22.

To limit heating of the operating mechanism 10 upon separation of thecontacts 2i) and 21, the toggle link 59 is provided with a hook-like endportion 80` that engages a suitably cutout portion 31 (lFiG. 2) in a berslide member 82. The slide member 82 reciprocates in a suitable recess13 in the base 12 upon movement of the toggle link 59.

As mentioned, the circuit breaker 10 may be manually operated to theopen and closed position by movement of the manual operator 5t).Movement of the manual operator 5t) in the clockwise direction from theposition shown in FIG. 1 to the open position, shown in FIG. 4, carriesthe upper ends 63 and 64 of the toggle link 59 to the left of the lineof action of the spring 65 thereby causing the spring to bias the togglelink 59 counterclockwise with a snap action. Counterclockwise movementof the toggle link jS9 is transmitted to the contact carrier 22 throughthe pin 71 which cooperates with the slots 72 and 73 in the Contactcarrier 22 to bias the contact carrier 22 counterclockwise to the openposition. Movement of the manual operator 50 in the Counterclockwisedirection from the open position (FIG. 4) to the closed position(FIG. 1) moves the upper ends 63 and 64 of the toggle link 59 to theright of the line of action of the spring 65 which then biases thetoggle link 59 clockwise with a snap action. Movement of the toggle link59 is transmitted through the pin 71 to the contact carrier 22 which isbiased clockwise to the contact closed position as shown -in FIG. 1.

Upon the occurrence of an overload or fault in an electrical circuitassociated with the circuit breaker 11, the latching sur-face 45 isretracted from under the end portion 70 of the releasable member 66.Upon release, the releasable member 66 rotates clockwise, as shown inFIG. 5, about the pivotal support `69 thereof carrying the spring 65past the fulcrums 57 and 58 in the manual operator 50. Rotation of thereleasable member 66 is arrested by a stop member 84.

The spring 65 then biases the toggle link 59 counterclockwise about thefulcrums 57 and 58 and the pin 71 thereon biases the contact carrier 22to the contact open position. Also, the manual operator 50l is biasedclockwise to a trip indicating position (FIG. 5) against a pin 85 on thereleasable member 66. The mechanism 10' of the circuit breaker 1-1 maybe reset after automatic operation thereof by moving the manual operator50' in the clockwise direction beyond the off position, shown in FIG. 4,to rotate the lower end portion 54 thereof into contact with the resetpin 35 on the releasable member 66. The

lower end portion 54 of the manual operator 50 upon further clockwisemovement thereof biases the reset pin 85 and the releasable member 66counterclockwise about the pivotal support 69 until the latching portion70 of the releasable member 66 reengages the latching surface 45 on thearmature 36. Subsequent counterclockwise rotation of the manual operatorSil to its closed position, shown in FIG. 1, closes the separablecontacts 2t) and 21 as described hereinbefore.

What is claimed is:

A circuit breaker comprising:

(a) an insulating enclosure having a rotary support for a manualoperator,

(b) a manual operator rotatably supported in said rotary support of saidenclosure,

(c) a stationary contact supported by said enclosure,

(d) a contact carrier rotatably supported by said enclosure,

(l) said contact carrier having a body generally U-shaped in crosssection including a bight portion and a pair of spaced leg portionsextending substantially perpendicularly therefrom,

(2) each of said leg portions having an elongated slot therein extendingsubstantially parallelly to said bight portion and each leg portion alsohaving a lateral extension pivotally connected at a free end portionthereof to said enclosure at a location closer to said stationarycontact than is said rotary support for said manual operator.

(3) said bight portion having an integral angularly disposed extensionforming an offsetting portion extending from an end of said bightportion remote from the pivotal connection of said lateral extensions ofsaid leg portions to said enclosure and extending in substantially thesame direction as the direction in which said leg portions extend fromsaid bight portion, and

(4) said osetting portion having an integral angularly disposed free endportion extending substantially parallelly to said bight portion andforming an offset extension thereof,

(e) a movable contact secured to said offset extension of said bightportion of said contact carrier on the side thereof facing in thedirection of extension of said leg portions from said bight portion,rotation of said contact carrier in opposite directions about thepivotal connections of said free end portions of said `lateralextensions of said leg portions to said enclosure respectively engagingsaid movable contact with said stationary contact and disengaging saidmovable contact from said stationary contact,

(f) a releasable member rotatably supported by said enclosure,

(g) a trip device supported by said enclosure and normally retainingsaid releasable member in a latched position, said trip device beingoperative in response to abnormal circuit conditions to release saidreleasable member from said latched position,

(h) a fulcrum on said manual operator rotatable therewith and locatedcloser to said stationary contact than is said rotary support for saidmanual operator,

(i) a toggle link rotatably supported by said fulcrum and interposedbetween said leg portions of said contact carrier,

(1) said toggle link having a body generally U-shaped in cross sectionincluding a bight portion and a pair of spaced leg portions extendingsubstantially perpendicularly therefrom toward said bight portion ofsaid Contact carrier,

(2) said leg portions of said toggle link having lateral extensionsrespectively engaging said fulcrum and also having actuating portionsthereon extending outwardly in opposite directions and respectivelyengaging said slots in said leg portions of saidcontact carrier, and

(j) an overcenter spring connected at one end to said bight portion ofsaid toggle link and at its other end to said releasable member at alocation closer to said stationary contact than is said rotary supportfor said manual operator and biasing said lateral extensions of saidtoggle link into engagement with said fulcrum while also biasing saidtoggle link for rotation about said fulcrum, said manual operator beingrotatable to rotate said ulcrum selectively in opposite directionsacross the line of action of said spring to thereby reverse the rotativebias of said spring on said toggle link and eifect rotation of saidcontact carrier in a direction opposite to the direction of rotation ofsaid manual operator, said releasable member being operative uponrelease from said latched position to carry the line of action of saidspring to the opposite side of said fulcrum from its relative locationin the latched position of said releasable member to thereby reverse therotative bias lof said spring on said toggle link, and said fulcrum inall positions of said manual operator being closer to the pivotalconnection of said contact carrier to said enclosure than to the pivotalconnection of said contact carrier at the slots thereof to the actuatingportions of said toggle link.

References Cited in the tile of this patent UNITED STATES PATENTS2,065,357 Von Hoorn Dec. 22, 1936 2,816,987 Hagdahl Dec. 17, 19572,889,428 Kingdon June 2, 1959 2,902,560 Stanback Sept. 1, 19592,920,161 Dessert Y Jan. 5, 196()

